Conference netcad::hub_mgnt

    Well I don't know how specific you want, but here goes.
    The 900 series bridges (oops switches) DECswitch 900EE,EF,TX,FO
    all rate limit the selected multicast address types to be included 
    in the rate limit category. Specified protocols (Ethernet protocol 
    type, SAP, or SNAP), can also be included in the rate limit if they 
    occur in any multicast packets. 
    I think the rate limit is set to default at 400 pps (packets per second). 
    So when rate limiting is enabled it will of course rate limit at 400 pps
    unless a different granularity is specified.
    The rate limit can be set with as small a granularity as 100 pps.
    The rate limiting is done over 10 ms (millisecond) time periods. So a 
    limit of 400 pps is translated to a limit of 4 per 10 ms period. At the 
    beginning of each 10 ms period a counter is set to 4. During the 10 ms 
    period, each time a multicast packet is seen that is subject to the rate 
    limit, the counter is decremented. If the counter reaches zero, the 
    packet is discarded.
   
    Bob   

    where is this documented?  How would a CUSTOMER find this out?
    
    Just curious,
    j
    

    Does the rate limiting only apply to multi-casts.
    
    If I assign a protocol filter and click on the little rate 
    limiting wristwatch are all packets with that protocol 
    type affected. BTW this is the desired behaviour.
    
    Since packets/frames can occur in a range of sizes
    but certain applications tend toward a grouping of packect sizes 
    what would be a rough translation of packets per second
    to megabits/sec for a typical TCP/IP internet/intranet Web 
    access enviornment. 
    
    
    For example, I would like to be able to restrict Web traffic to
    aprox 2mb/s on a specific bridge. What would I set the pps 
    value to.  To take this futher since the rate limiting is per device
    ,e.g. EF unit, how would this break down on a per port basis.
    
    If I establish a 2meg rating for the unit does that mean all 
    6 ports contend for 2meg access from the FDDI side of the network.  
    
    
    
    
    Jim
    
    

    Rate Limiting *only* applies to multicast frames, and only 
    those multicast frames that you have specified by address or
    protocol type. 
    
    Bob

    My sources are Engineering Specs etc. and my own working knowledge.
    You can also find references and mention of rate limiting in some 
    of the network related notes file (Ethernet, FDDI etc). These sources
    aren't available to customers of course.
    
    Rate limiting is in fact discussed in the DEChub Network Modules 
    900-Series Switch Reference, along with a lot of other useful 
    information. The document is available to customers on the NPB web 
    site in both postscript, and pdf format.
    
    http://www.networks.digital.com/dr/hubs/switches/manuals/
    Tell your customer to click on either of the first 2 links.
    
    Bob

    A ah!  ANOTHER Web-centric thing that does the customer (who buys it)
    no good until they get their (@#$*($*( network up, running, and then
    FINALLY install the junk on their PC and get to the WEB.
    
    We probably need to  make it ORDERABLE or give it away with each hub.
    
    You know, even Cracker-Jack put a prize in each box....
    
    REgards,
    j
    

    Jon....chill
    
    There are a lot of customers (whether you realize it or not), that
    already have some sort of access to the web, and hopefully they
    get a copy (courtesy of you), of NETCOM News, with all the nice
    stuff (and the little pointers to our web site), so they can peruse
    and find what it is they want to ask you more questions about when
    you visit them.
    
    Have a nice holiday weekend,
    Bob

    
    
    	Off topic, but, what is NETCOM News?
    
    Scott

    NETCOM News is published every two months by Digital's Network
    Product Business Marketing for Digital's Network Sales and Business 
    Partners. I think you can send email to [email protected] 
    asking to be put on the distribution mailing list. Or if you send mail 
    to the Managing Editor Amie Smith on TNPUBS::A_SMITH you can get 
    assistance. I don't know if this publication can be subscribed to via 
    the vtx_profile method or not.
    
    Bob

    
    
    Thanks for the pointer
    
    Scott

    NETCOM News is also the name of newsletter for the large ISP located
    in San Jose, CA.
    
    Mark